Background and purpose: Laundry is one of the main wastewater producing units in hospitals. Most of detergent materials are hardly degradable and cannot be broken fast in the conventional treatment facilities. This research aimed at studying the possibility of hospital laundry wastewater pretreatment by electrocoagulation method using aluminum electrodes.

Materials and methods: Using composite sampling method, a total of 72 samples was taken from the effluent of a hospital laundry wastewater in Gorgan. The samples were analyzed according to standard methods of water and wastewater examination. After determining the quality of raw laundry wastewater, the wastewater was treated by electrocoagulation method with aluminum electrodes in different circumstances of pH, voltage and times. Process efficiency concerning the removal of COD, color, phosphate and surfactant was examined.

Results: In this study the mean density of COD, phosphate and surfactants in hospital laundry waste water were 848.8 ± 109.4, 1.03 ± 0.06 and 4.81 ± 0.93 mg per liter, respectively and the mean concentration of color was 759.3 ± 152.8 TCU. In optimal conditions, this process could remove 86, 98.8, 94.98, and 66.6% of COD, color, phosphate and surfactant, respectively. The efficiency removal of all parameters increased as the voltage and the contact time increased.

Conclusion: This study showed that laundry waste water was highly polluted and electrocoagulation process could be an efficient procedure in its pre-treatment.